In "White Noise," Jonathan Rivers (Michael Keaton) is contacted by his murdered wife, Anna (Chandra West), who wants him to stop her killer from striking again. It's hard to say no to the woman you love, especially if she goes to the incredible trouble of speaking to you via electronic voice phenomena from the grave.

What happens after we die is one of the greatest questions facing mankind (along with "Where'd that other sock go?" and "Why does he keep saying 'nucular'?"). There are many theories as to what kind of afterlife (if any) exists, but according to Hollywood, it's probably not a restful place. Because in film, the dead have a really annoying habit of pestering the living.

Blame it on Shakespeare. The Bard made the murdered king of Denmark appear before Hamlet, revealing the treachery of Claudius and asking his son to avenge his death, thus inspiring about a million fictional specters. Not to mention dozens of film adaptations of "Hamlet," from Georges Méliès' 1907 French silent film to the 2000 contemporary update starring Ethan Hawke as a corporate Hamlet and Sam Shepard as the ghost of his CEO father. Most consider the 1948 "Hamlet" with Laurence Olivier both starring and directing to be the quintessential version. Rent them all and judge for thyself.

Another literary spirit that's gotten tons of screen time is Jacob Marley in Charles Dickens' "A Christmas Carol." The ghost of Ebenezer Scrooge's old business partner comes knocking through the door and tells the old man (who is quite set in his ways) that he has to change his entire lifestyle. Scrooge is skeptical about the visit, thinking Marley's ghost is a hallucination, the by-product of undercooked food, so what does Marley do to convince him? Pulls out that old spectral standby "Boooooo!" as he rattles his ponderous chain before warning Ebenezer that three more spirits will visit him though the night. And it's Christmas Eve, fer cryin' out loud!

Thankfully, not all ghosts are such killjoys. Take the Kerbys, Marion (Constance Bennett) and George (Cary Grant), a cosmopolitan couple who take a wrong turn into a tree one champagne-sippin' night in the 1937 screwball comedy "Topper." The Kerbys' ghosts come back to haunt their pal Cosmo Topper, but not to make him repent or avenge anything — they just want him to lighten up and enjoy life a little more. Leave yer nagging henpecking wife at home and come toss down some pink ladies (that's a drink, kids)! Life's too short. We need more ghosts like this.

It's probably not a good idea to become a source of entertainment for bored spirits. They can be a demanding audience, as the blind monk singer Hoichi learns in one of the tales in the 1965 Japanese film "Kwaidan." Hoichi's music is so beautiful that it raises spirits who demand he sing to them every night. Asian film is full of stories of ghosts who don't play well with others, so you can imagine that a two-song encore doesn't exactly satisfy the otherworldly music lovers.

Imagine if the fate of the galaxy were resting firmly on your geeky farm-boy shoulders. Wouldn't the last thing you'd need be the ghost of Obi-Wan Kenobi popping up and reminding you to "use the force"? Throughout "Star Wars" (1977) and its original sequels, "The Empire Strikes Back" (1980) and "Return of the Jedi" (1983), the Jedi master (Alec Guinness) belabors the obvious to Luke Skywalker (Mark Hamill), as if being constantly berated by Yoda weren't enough. "Use the force! Trust your feelings! Brush your teeth!" Hey, old man! Trying to destroy the Death Star here! Need to concentrate!

You'd think that, being trapped alone with just your google-eyed wife and wacko kid in a huge hotel in the middle of nowhere during wintertime, you'd be grateful for a little company, even of the spectral variety. But when the ghosts in "The Shining" (1980) start suggesting that Jack Torrance (Jack... oh, you know) pull a Lizzie Borden on his family, utter solitude doesn't seem like such a bad thing. Oh, and let's not forget the ghosts of the two little girls trying to get Jack's Big Wheel-riding son Danny to "come and play ... forever ... and ever ... and ever." For our money, the single scariest scene in motion picture history.

At least ghosts are usually visually innocuous. They're often wearing their Sunday best or one of those white diaphanous deals that never go out of style (the spectral equivalent of the little black dress). But in 1981's "An American Werewolf in London," David Kessler (David Naughton) has to deal with a group of ghosts, which includes his best friend Jack (Griffin Dunne), that are bloody and have decomposing flesh and encourage David to kill himself. But David really can't complain that much, since he's the wolfman who ripped all of them to pieces. Our actions have repercussions, David! But that little dangling flap of skin on Jack's shredded cheek is really gross.

In the ultimate chick-ghost-flick, "Ghost" (1990), the restless spirit of Sam (Patrick Swayze) enlists the aid of a most annoying medium, Oda Mae (Whoopi Goldberg), to contact his beloved Molly (Demi Moore). The movie tries to make you think it's because Sam's trying to save her from falling in love with his scheming partner (Tony Goldwyn), but actually it's because, dead or not, nobody wants to give up that incredible SoHo loft they just bought.

It's no wonder Cole Sear (Haley Joel Osment) is a troubled kid in 1999's "The Sixth Sense." Not only does he have to say awful dialogue and put up with insultingly obvious production design (ooh, a red doorknob!), he's haunted by tons of dead people. And his psychoanalyst, Malcolm (Bruce Willis), having totally lost his own grip on reality is of no help at all. We'd recommend that Cole have his mother buy him the complete EC Comics horror library so he won't be troubled by the restless spirits anymore ... because he'll be familiar with all of their stories.

The point is, whether they're haunting your house ("The Uninvited," "The Amityville Horror," "House on Haunted Hill," "The Haunting," "Poltergeist," "The Legend of Hell House," "13 Ghosts," "Burnt Offerings," "Beetlejuice" and a skillion more) or asking you to avenge their death ("The Innocents," "Stir of Echoes," "What Lies Beneath," "The Ring," "Gothika"), ghosts can be a real pain in the butt. Too bad they can't all just be friendly ... y'know, like Casper.